6. Why is the drug azidothymidine (AZT) block the growth of the AIDS virus HIV. (2%)

4 ) Many drugs used in the treatment of psychotic disorders are dopamine antagonists. Dopamine antagonists (select the correct descriptions that apply): (3%) (a) are drugs that bind to Dopamine receptors (b) do not activate Dopamine receptors (c) do activate Dopamine receptors (d) can block the actions of dopamine (e) can trigger similar actions as dopamine (f) has a greater Kd to the receptor than Dopamine

5 ) When Dopamine signals to Dopamine receptors D1/D2 complex, Phospholipase C is activated. What are the downstream second messengers of GPCR-Phospholipase C (PLC)? (2%) (a) NO and cGMP, and calcium (b) IP3, DAG, and calcium (c) protein kinase C (PKC) (d) cAMP and calcium

6) Ca2+ is an important second messenger in many signaling pathways. Please describe how the increase in intracellular Ca2+ concentration may promote the maturation and release of Insulin in beta cells. (4%)

5. In which direction along the template must the RNA polymerase in Figure below be moving to have generated the supercoiled structures that are shown? Would you expect supercoils to be generated if the RNA polymerase were free to rotate about the axis of the DNA as it progressed along the template? (4%)

1) How does this phage replicate its DNA?

2) Do you think any progeny phage will be 14C-labeled?

1 ) A telomere allows a chromosome to be replicated precisely so that no nucleotides are lost from the end of the chromosome, thereby solving the end-replication problem.

2 ) Nuclease-hypersensitive sites in chromatin are located in the linker DNA between nucleosomes.

3) If a DNA-binding protein forms a symmetric dimer, it is likely that the recognition site in the DNA is symmetric as well.

4) In general, the DNA replicating enzyme in E. coli is DNA polymerase I.